Throat plate



y 28, 1959 G. H. MCKINLEY ETAL' 2, 9

THROAT PLATE Filed Sept. 9, 1958 FIG. 2.

FIG. '4.

INVENTORS GEORGE H. MCKINLEY & YRICHARD H. WHITEHEAD d 'U/b 1 m7 ATTORNEYS United States Patent i THROAT PIJATE George H. McKinley and Richard H. Whitehead, Laconia, N.H., assignors to Scott & Williams, Incorporated, Laconia, N.H., a corporation of Massachusetts Application September 9,1958, Serial No. 759,899 9 Claims. (Cl. 66125) This invention relates to a throat plate for a knitting machine particularly adapted to stand up during the knitting of abrasive yarns. I

In circular knitting machines of the type particularly used for the production of hosiery it has generally been necessary to provide a guide over which yarn is led from an active yarn feeding finger in a definite path to the needles. The guiding element so provided is generally known as a throat plate, and a typical example of such a throat plate in a machine is shown in the patent to Scott No. 1,282,958. A throat plate of this type is fitted into an opening in the latch ring which surrounds the upper part of the needle circle and is open at its top to permit the introduction of yarn feeding fingers into active position and their removal therefrom. Quite generally at a single feed point in such machines a plurality of yarn fingers are provided which when in active position are held downwardly against and positioned by a rest surface or platform provided in the throat plate, the fingers being held in active position by spring pressure. Since such fingers are conveniently located side by side, and thus occupy different positions on the throat plate when active, to secure uniform feed to the needles of all of the yarns the throat plate is provided with an opening which provides a pair of recesses at shoulders through and from which the yarns are guided to the needles during rotary and reciprocatory knitting, one of the recesses being active during rotary knitting and during forward strokes in reciprocation, while the other of the recesses is active as a guide during reversereciprocatory strokes.

For the knitting of yarns of cotton, wool, rayon or the like, throat plates of hardened steel were quite satisfactory and the recesses would stand up very well against Wear because these yarns had only minor abrasive qualities. However, with the introduction to the knitting industry of thermoplastic yarns, and particularly those of fine denier monofilament type there was presented a serious problem due to the abrasive properties of such yarns, the yarns causing grooves to be worn in the throat plate particularly at the corner providing the feeding recess for the yarn during rotary knitting. The groove, when cut sufiiciently deep by the abrasive action, was only the width of the yarn and would prevent the passage of a knot and consequently would cause the yarn to break. Increased friction also resulted on the yarn due to its effective greater circumferential engagement with the abraded groove.

A solution to this problem seemed to be oifered by providing at least at the recess-forming portion of the throat plate an insert consisting of a molded piece of hard ceramic material cemented in position. While this material was of sufiicient hardness to resist cutting by the yarn, it was also extremely brittle and presented other problems such as cracking and chipping without apparent cause while in use. It seemed possible that such damage was due to vibration and at least in part to that caused by shocks transmitted to the ceramic inserts due to the blows 2,896,434 Patented July 28, 1959 of yarn fingers falling on the metallic floor of the throat plate when going into action.

In accordance with the present invention a throat plate is provided in which a hard brittle ceramic guide-forming insert is provided but which is quite free of the deterioration or destruction by cracking and shipping such as was previously observed. In accordance with the invention the insert is secured to the throat plate by means of a leaf spring arrangement which protects the insert from the transmission of damaging shocks. The arrangement is further advantageous in providing for convenient replacement of the ceramic inserts if for some reason to:

placement becomes necessary.

The objects of the invention relate to the provision of a throat plate having the desirable characteristics above indicated and further objects of the invention relating to details of construction and operation will become apparent from the following description, read in conjunction with the accompanying drawing, in which:

Figure 1 is a top plan view of a desirable form of throat plate provided in accordance with the invention; Figure 2 is an elevation of the same looking outwardly from the center of the needle circle;

I Figure 3 is a bottom plan view of the same;

Figure 4 is a side elevation of the same looking at the right of Figures 1, 2 and 3; and

Figure 5 is a perspective view illustrating the association of the throat plate with a typical yarn feeding finger and the needles.

The throat plate which is illustrated comprises a supporting element 2, which may be of steel or other material, which is formed with a platform 4 and upwardly extending sides 6, the sides being provided with sockets 8 aligned with the inner edge 10 of the platform 4. The supporting element 2 is arranged to be secured to the usual latch ring, in a recess of the latter, by screws passing upwardly through elongated shouldered openings 12 which provide for radial adjustment with respect to the latch ring and the needle circle. Such a mounting of the usual throat plate is conventional.

.In accordance with the present invention the insert portion of the throat plate is provided by a ceramic insert er -element 14 which in its intermediate portion has an upper surface 16 normally aligned with the upper surface of the platform 4, and which at its end portions is pro vided with upward extensions 18 engageable within the sockets 8 and, when properly positioned, aligned with the adjacent surfaces of the element 2. As will immediately appear spring action urges the end portions 18 of the insert 14 against the portions of the supporting element overlying the sockets 8. The inner edge 20 of the insert 14 is arcuate and concentric with the axis of the needle cylinder so as to extend circumferentially in close proximity to the needles.

When in its normal postion the bottom surface 22 of the insert 14 projects slightly below the lower surface of the supporting element 4 and is cemented to the inner portion of a supporting leaf spring 24 which is secured to the supporting element 4 by means of screws 26 passing through openings in the leaf spring 24 and tapped into the supporting element 4. The openings in. the leaf spring are desirably somewhat larger than the shanks of the screws 26 so that fine adjustments of the lateral and radial positions of the insert with respect to the supporting element may be made.

The insert 14 is desirably cemented to the supporting spring 24 by the use of a suitable cement such as an epoxy resin cement. It has been found desirable to provide holes 28 through the spring in the region of cement? ing not only to provide for visual inspection of the proper flow of the bonding cement but also to provide effective 3 dowelling of the insert to the spring by the entry of cement into the holes to provide plugs.

The insert 14 most desirably is provided by a hard,

non-metallic molded ceramic material which, however, though it has excellent abrasion-resisting properties is very brittle. A highly desirable type of ceramic insert is provided as disclosed in the patents to Thurnauer 2,214,703 and 2 ,369,266, dated, respectively, September 10, 1940, and February 13, 1945. Various similar ceramic materials are known having similar abrasion resisting qualities but, at the same time, having brittleness which results in chipping or cracking and consequently expensive inoperative periods of the knitting machines. In accordance with the present invention the resilient type of mounting which has been described avoids damage to inserts by preventing the transmission thereto of vibrations such as those occasioned by the dropping into action of yarn fingers. The invention, of course, is applicable to various materials suitable for abrasion resistance but having brittle characteristics. Figure particularly shows the assembly of the improved throat plate with yarn feeding devices and the needles. A single yarn feeding finger 30 is illustrated in its active position, feeding a yarn 32. It will be understood that .in accordance with usual practice there may be a number of such yarn fingers located side by side and arranged to be either singly or in groups lowered to active positions in which they rest ,upon the platform 4 under spring action, the yarns such as 32 feeding through eyes in these fingers which have their exit ends slightly raised above the level of the platform. Conditions for rotary knitting are shown in Figure 5 and in this case the yarn 32 runs to the needles 34 which are rotating in a counterclockwise direction. A left-hand recess 36 actually determines the path of the yarn to the needles and is provided by the corner between the upper surface 16 and the left-hand upright portion 18 of the ceramic insert. As will be evident from Figure 5, yarns will pass through this recess to emerge therefrom in similar paths irrespective of the lateral positions of the several yarn fingers. A corresponding recess at the right of the throat plate determines the path of feed during reverse reciprocatory strokes of knitting.

As will be evident from considering the foregoing,

similar recesses provided in metallic throat plates would be subject to abrasive grooving by thermoplastic yarns such as nylon or the like, and such gooves when deep enough, would arrest knots causing yarn breakage. The

W a of our p ar ly occurs d n rota y knit ng, reciprocatory knitting generally occurring during only a relatively small fraction of the formation of a stocking unless split work or reciprocatory patterning is taking place. It will accordingly be understood that in accordance with the invention the ceramic insert may be confined in many machines only to the region providing the guiding recess for rotary knitting.

It will be evident that various changes may be made in the specific embodiment of the invention without departing from the scope thereof as defined in the following claims.

What is claimed is:

1. A throat plate for knitting machines comprising a supporting element adapted to be secured to a knitting machine, a hard, brittle, non-metallic element providing at least one yarn guiding recess, and a spring member mounting the last mentioned element resiliently on the first mentioned element.

2. A throatplate according to claim 1 in which said spring member is inthe form of a leaf spring.

3. A throat plate according to claim 2 in which the spring member iscemented to the last mentionedelement.

4. A throat plate according toclaim 1 in which the first mentioned element has a platform arranged to .be engaged by, and to position, an active yarn finger.

5. A throat plate according to claim 2 in which the first mentioned element has a platform arranged to be engaged by, and to position, an active yarn finger.

6. A throat plate according to claim 3 in which the first mentioned element has a platform arranged to be engaged by, and to position, an active yarn finger.

7. A throat plate according to claim 1 in Whichthe second mentioned element is of ceramic material.

8. A throat plate according to claim 2 in which the second mentioned element is of ceramic material.

9. A throat plate according to claim 3 in which the second mentioned element is .of ceramic material.

References Cited in the file of this patent UNITED STATES PATENTS 1,523,337 Zoreczky Jan. 13, 1925 2,147,063 Sanford Feb. 14, 1939 FOREIGN PATENTS 13,274 Great Britain ....Oct. 10, 1850 813,823 Germany Sept. 17, 1951 

